Just wonderin, I am building a 300 with 11.5:1 Static CR and I want to throw a little cam at it. How much cam can I get away with without hurting my mileage too much? I will be running either 92 or E-85 through a carb and eventually I will go to a dual 2.8l tbi setup with megasquirt. I am running 2.75:1 gears in a 9" rear end with 28" tall tires, and a stock C6 tranny. Will install a shift kit in the tranny hopefully soon. All this is in a 1984 Ford E-150 that weighs approximately 4750 lbs.

Look at Comp Cams Extreme energy grinds for the sbf especialy the 262-274 grinds. I'm not an expert on any of this stuff but think they would work good in our motors if you concentrate on producing torque. The gears i would suggest 3.55-3.73 to help get the weight moving.

No hostility intended by this. I'm sorry I didn't specify this thing's use. It will be used mainly for towing a trailer and driving myself around. BTW, you would've been surprised to see what this thing was like when my engine wasn't worn out. It actually accellerated pretty good. That was with less than stock torque and horsepower when the thing weighed 5000 lbs. And I said the wrong weight, it's now closer to 4500 lbs, which isn't much heavier than your average full size pickup. They put the 2.75 gears in LOTS of 9" rear ends from the factory. And another thing about my fuel, 92 will be fine and I also stated I would run E-85 too which is 97+ octane, my father built an engine with domed pistons and it ran beautifully on pumpgas, and my friend runs his turbo 3.8 gokart on 87 with 9.4:1 and it doesn't start pinging till it hits 6 PSI of boost which would calculate to approximately 13.2:1 CR after boost. Thanks.

_________________1990 F-150, 4.9l, C6

Sat Dec 26, 2009 11:37 pm

80broncoman

Global Moderator

Joined: Sat Oct 18, 2003 10:49 pmPosts: 5527Location: The Great state of Ohio!!

Re: 300 I6 Cam ideas

Lazy JW wrote:

With that much compression you do NOT want a short-duration, RV-type cam; make it at least 270º with a wide LSA so as to have a late intake closing event and you might get away with it. Maybe.Joe

Joe is right on this one. 11.25 comp doesn't go with a "little cam"In fact 1 11.25 compression ratio, 2 4500 lbs, 3 towing, 4 MPG, 5 2.75 gears . Usally one of these is NOT found with the others. One exception with propane,E85, straight alky, fine but if you run out do NOT try to run it on ANY 87 octane.

..........my friend runs his turbo 3.8 gokart on 87 with 9.4:1 and it doesn't start pinging till it hits 6 PSI of boost which would calculate to approximately 13.2:1 CR after boost.....

Please do not misunderstand, there is a world of difference between trailer towing for long periods of time and short-duration gokart acceleration.

There is a reason why the Ford engine designers actually REDUCED the compression ratio on the Heavy Duty 300's that were destined for use in the larger trucks (up to 26,000 lbs gross). I have no idea what your trailer towing scenario involves, but any time you tie a tail onto a pickup it is wise to consider the consequences.Joe

If you're intent on keeping the 2.75 gears, you're going to want an engine/trans build that makes beaucoup torque at low RPM and maintains a wide torque band to carry you through the gears. The cam that does that (as JW pointed out earlier) is not compatible with 11.5:1 compression. In the long run you're going to be much happier with a 9.0:1 CR (or less), an RV cam and a WR gearset in that C6.

So other than being able to brag that you have 11.5:1 compression, why exactly do you want it? The increases in performance that you get from that sort of a CR are more than offset by the loss of usable RPM range that it also creates, not to mention the additional expense of premium (or better) fuel.

filling the cylinder (within a particular rpm range) involves an area under the lift curve and starting points and closing points in relation to piston position, read in terms of crank rotation. the engine's static compression is pretty much matched to supplement the engine dynamic compression capability, maintaining a good margin of dynamic compression which produces good torque and utilizing the inlet charge as well as possible (volumetric efficiency). Knock rating of the fuel dictates how much of a positive margin of dynamic compression the motor can tolerate, and use to its benefit.

high static compression is required when valve events are positioned in a manner (typically wider) that dynamic compression is compromised. Those valve events typically will not produce as clean of off-idle response and extreme low end that conservative valve events would. The reason being the wider valve events are more productive at the higher rpms.

When conservative valve events are dictated but there is a mismatch in regards to the static compression, the main thing that has to occur is for the motor (ignition and dynamic compression primarily) to be fooled into thinking everything is right. This means the seat events need to be widened and the position of the exhaust lobe in such a manner to start the evacuation earlier (killing cylinder pressure). In short, wider seat durations, lazy ramp rates, and earlier exhaust events (typically as a wider lobe sep angle). Likewise on the flip side, too low of static compression needs to be met with narrower seat events and higher ramp rates.

Basically, you take cylinder filling (performance) capability away from the motor and let the higher static compression fill in that gap. If you have regular selection of higher octane fuels then that cushion can be absorbed somewhat, but you have to acknowledge that as a tow vehicle and high rear-end ratio that your rpm range is going to be optimized in pretty low ranges (1800-2400). Valve events that promote performance in this range, paired up with a pretty serious static compression, even with good fuel, are not going to be something that a blind stab at a cam catalog based on rpm range alone is going to compensate for.

_________________It doesn't run quick at the track, but it gets long stares wherever it goes.Never in a million years did I think I would have an antique hot rod truck, much less with its own name emblazoned on the front fender and a freakin' six cylinder for power; but it is a Ford, it is old, and it is definitely one of the funnest vehicles I have driven.

Mostly a street/strip vehicle .Check online at CompCams.com, Check their profiles for the sbf Exreme Energy grinds,I'm using the Extreme Energy 262 in my motor and someone else used a similar grind in a 200,motor put out 1 hp per cu.in. You'd would probably be better off with something within the lower rpm range for towing etc.

That cam sounds like what I am looking for to run in my nostalgia altered car. Good zoom zoom and minimal valvetrain maintenance.

Send it to me.

_________________FORD 300 INLINE SIX - THE BEST KEPT SECRET IN DRAG RACING

Tue Dec 29, 2009 11:23 pm

82F100

Global Moderator

Joined: Sat Nov 09, 2002 12:00 amPosts: 1644Location: Phoenix , AZ

Re: 300 I6 Cam ideas

FTF, that grind is for a 351W, saw some other grinds especially in the FE section of their catalog same cam series( Xtreme Energy) that would be interesting to try in a 6.

_________________300's make good truck motors....not race motors

Wed Dec 30, 2009 1:07 am

THE FRENCHTOWN FLYER

VIP Member

Joined: Sat Nov 09, 2002 10:25 pmPosts: 4736Location: FRENCHTOWN

Re: 300 I6 Cam ideas

My bubble has been burst.

_________________FORD 300 INLINE SIX - THE BEST KEPT SECRET IN DRAG RACING

Wed Dec 30, 2009 1:09 am

84FordVan

Registered User

Joined: Fri Sep 18, 2009 9:40 pmPosts: 75Location: Mankato, MN

Re: 300 I6 Cam ideas

StrangeRanger, that's the exact cam I was looking to run. I actually stumbled on it by mistake when looking through cams on their site. Sounds like one heck of a deal, cam and kit all for 440$. Can't really go wrong there. Nice 114* lobe center on that one too, I like that.

Who is online

Users browsing this forum: Bing [Bot] and 3 guests

You cannot post new topics in this forumYou cannot reply to topics in this forumYou cannot edit your posts in this forumYou cannot delete your posts in this forumYou cannot post attachments in this forum